HI. IE SIIAUK. 



1131 



N. Mag. Naturv., Bil -211 (1K«4). p. lllj; DOiii'.ui. , .)/'!». 

 Iltiol. Medit., fasc. 11, p. 42; Lii.ij., ,Sv., .Xori/. Fun, 

 FM:, vol. Ill, p. COO. 



Ill IMmIc L, tig. 3 we give a representation of m 

 young l>liie Shark, 41 cm. long, from tlie Indian Ocean. 

 It was cut out of the lielly of the niothcr-tisli. The 

 specimen is .sufficiently developed and well preserved 

 enough to give a Ijetter idea tiian a stuffed e.xamph! 

 of the appearance of the species. Tlic IJhie .Shark, 

 however, attains a considerable size, in ordinary in- 

 stances a length of 2 to 3 or 4 m.", and tlie form 

 varies during growtli. Tlie pectoral fins become con- 

 siderably longer and narrower, their length being some- 

 times thrice their breadth. The relative size of the 

 eyes diminisiies from aliout ' '; to ',,„ of the length of 

 the head. The form of the jaw-tcctli (fig. 32fi) is 

 altered as shown in the figure; and the number of 



specimen 3' ., m. long was taken in Ti-aveniiinde Hay 

 and described by W.m.bai m''. During the previous 

 year a specimen is s:iid to have been caught off KieP. 

 According to Coucu the Blue Shark roves round the 

 English coast during summer, but leaves those water.s 

 at the a])proach of winter. 



Though the r.lur Sliai'k attracts most attention as 

 it swims at the surface, it also descends to a consider- 

 able dc])th (at least about 100 m.), and here is perhaps 

 its most congenial home. Light is apparently obnoxious 

 to it, for at the surface and in the upper strata of the 

 water, so long as the light is powerful, and when it is 

 desirous of fixing a steady gaze on some object, it keeps 

 drawing the nictitating membrane up and down over 

 its eyes. In the Mediterranean the young make their 

 appearance during ^lay and June (Doderlein). Oppian 

 celebrated in verse' the care devoted by the parents 



^V' 



^■v. 



,0;^n4'^i^iW 



H 



^^^^^^-^hh^hhhh 





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Fii.'. 32<!. .Ia\v-ti?eth of tlie right side in a youiiK (.4) and an adult (B) Blue Shark. ' ., nat. size. After MOli.er and Henle. 



their transverse rows, one behind the other in each 

 jaw, increases from 2 to .5. 



In the tropical seas the Blue Shark is dispersed all 

 round the globe. In Europe it is common in the Medi- 

 terranean and at least not rare on the south coasts of 

 England and Ireland. Even in St. Andrews Bay (Scot- 

 land), according to McIntosh, it is not uncommon, 

 and according to Couch it strays up to the Orkney Is- 

 lands; but further to the north and east it is appa- 

 rently but an occasional visitor. In November, IcSSS, 

 • 'oLLETT received a specimen 16 dm. long that had 

 been taken at the very head of Christiania Fjord, and 

 Blue Sharks have been caught in the westernmost parts 

 of the Baltic. At the beginning of October, 17.53, a 



to their oft'sjiring. \\'hen any danger threatens, the 

 mother (or, according to others, the father) opens its 

 mouth for the young to take shelter in its pharynx' or 

 even in its stomach. The fry are, however, soon ca- 

 pable of defending and feeding themselves, for they 

 come into the world fully developed for leading an 

 independent existence, and measuring, according to a 

 note of VAN Beneden's-', at least 60 cm. 



The diet of the I^lue Shark consists principally of 

 fish of all kinds. In the stomach of a specimen 6 ft. 

 long Couch foutid a large Picked Dog-fish and a Con- 

 ger, both bitten right in two, and a Gurnard. In an- 

 other he found four Mackerel, half a Garpike, and so 

 many Herrings, (luite whole, that the fisherman sold 



" LlLUEBORG states as niuoli as 7' ., m. 

 * Cf. Bloch, 1. c. 

 ' Cf. MoBins and Heincke, 1. c. 



' Halieuticorum lib. 1. From the beginning of the third century, A. D. 



■ Cf. the method employed by the ChromidcB of preserving their eggs and fry in the branchial cavity. AOASSIZ. A Journey in 

 Uracil, p. 222. 



■' Poisn. Coles Belg., p. 4; Mem. Acad. Roy. Belg.. torn. XXXVIII (1871). 



